CN110988608A - Oil gas formula transformer bushing on-spot ac withstand voltage test device - Google Patents
Oil gas formula transformer bushing on-spot ac withstand voltage test device Download PDFInfo
- Publication number
- CN110988608A CN110988608A CN201910899750.XA CN201910899750A CN110988608A CN 110988608 A CN110988608 A CN 110988608A CN 201910899750 A CN201910899750 A CN 201910899750A CN 110988608 A CN110988608 A CN 110988608A
- Authority
- CN
- China
- Prior art keywords
- oil
- transformer
- gas
- bushing
- insulating sleeve
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R31/00—Arrangements for testing electric properties; Arrangements for locating electric faults; Arrangements for electrical testing characterised by what is being tested not provided for elsewhere
- G01R31/12—Testing dielectric strength or breakdown voltage ; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01R—MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES
- G01R27/00—Arrangements for measuring resistance, reactance, impedance, or electric characteristics derived therefrom
- G01R27/02—Measuring real or complex resistance, reactance, impedance, or other two-pole characteristics derived therefrom, e.g. time constant
- G01R27/26—Measuring inductance or capacitance; Measuring quality factor, e.g. by using the resonance method; Measuring loss factor; Measuring dielectric constants ; Measuring impedance or related variables
- G01R27/2688—Measuring quality factor or dielectric loss, e.g. loss angle, or power factor
- G01R27/2694—Measuring dielectric loss, e.g. loss angle, loss factor or power factor
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Power Engineering (AREA)
- Testing Relating To Insulation (AREA)
Abstract
本发明涉及一种油气式变压器套管现场交流耐压试验装置，包括与SF6气瓶连接的绝缘套筒和与滤油机连接的变压器油槽，绝缘套筒设置在变压器油槽上方，绝缘套筒顶部设置有加压端，加压端通过绝缘套筒内的导电弹簧与设置在绝缘套筒内的变压器侧油套管顶端电气连接；变压器侧油套管底端与设置在变压器油槽内的GIS侧SF6气套管顶端连接，GIS侧SF6气套管底端为接线端子，被套装在均压罩内，起到均压作用，有效避免尖端放电。本发明适用于所有电压等级油气式变压器套管，使油气套管两端同时置于相应的试验环境，保证试验条件符合相关标准，确保相应等级油气式套管的耐电强度，准确评估其绝缘水平，从而满足交流耐压试验和局部放电试验要求。
The invention relates to an on-site AC withstand voltage test device for oil and gas type transformer bushings, comprising an insulating sleeve connected with an SF6 gas cylinder and a transformer oil tank connected with an oil filter. The insulating sleeve is arranged above the transformer oil tank, and the top of the insulating sleeve A pressurizing end is provided, and the pressurizing end is electrically connected with the top end of the oil bushing on the transformer side arranged in the insulating sleeve through the conductive spring in the insulating sleeve; the bottom end of the oil bushing on the transformer side is connected with the GIS side arranged in the oil tank of the transformer. The top of the SF6 gas bushing is connected, and the bottom end of the SF6 gas bushing on the GIS side is a terminal, which is sheathed in a pressure equalizing cover, which plays a role in equalizing pressure and effectively avoids tip discharge. The invention is suitable for all voltage levels of oil and gas type transformer bushings, so that both ends of the oil and gas bushings are placed in the corresponding test environment at the same time, so as to ensure that the test conditions meet relevant standards, ensure the electrical strength of the oil and gas type bushings of corresponding grades, and accurately evaluate its insulation. level, so as to meet the requirements of AC withstand voltage test and partial discharge test.
Description
Technical Field
The invention relates to an oil-gas type transformer bushing field test device, in particular to an oil-gas type transformer bushing field test device with a voltage level of 35kV or above, which is applied to the field of connection and acceptance of 'oil-gas type' bushing transformers in new construction or modification and extension projects of a power system.
Background
The oil-gas type sleeve transformer is also called a transformer bank composite combined electrical appliance, and means that a high-voltage lead-out wire of the transformer is not led out through a capacitive sleeve, but is directly connected with the GIS combined electrical appliance. According to the standard requirements of the electric equipment handover test standard (GB50150-2016) of the installation engineering of the electric device, an alternating current withstand voltage test project and a dielectric loss tangent value test project are required to be carried out before the oil-gas type casing pipe is installed. If the oil-gas type casing pipe is found to be out of order or overhauled, an alternating current withstand voltage test is carried out to check the oil-gas type casing pipe, so as to identify the electric strength of the equipment and judge whether the equipment can continue to operate.
At present, in a new construction or a modification or an extension project of a transformer substation, a trend of adopting a GIS combined type device is provided, and a large number of oil-gas type sleeve transformers, also called transformer bank combined type combined electrical appliances, are inevitably introduced, namely, a high-voltage lead-out wire of a transformer is not led out through a capacitive sleeve, but is directly connected with the GIS combined electrical appliances. Thus, a large number of oil and gas type casings are used in cooperation.
One end of the oil-gas type sleeve is 'transformer oil' and the other end of the oil-gas type sleeve is connected and insulated with 'SF 6 gas', and the method of a pressurization test by inserting the tail end of the traditional oil-immersed type sleeve into a test oil groove is not feasible, because the other end of the oil-gas type sleeve is required to be in an 'SF 6 gas chamber', or external flashover discharge occurs because the creepage distance is not enough.
Because no device suitable for the oil-gas type casing pipe test is arranged on the site, the insulation resistance and the insulation dielectric loss tangent value of the oil-gas type casing pipe are only measured on the site at present. The potential safety hazard still exists in doing so, can't discover the insulating defect of slight concentration in the sleeve pipe, does not have an overall assurance to its electric strength, does not have the accurate evaluation of its insulating level of way, has left huge potential safety hazard to whether can take place the insulating accident in the operation of future.
If an oil-gas type transformer bushing which is completely suitable for various voltage grades can be developed, the two ends of the oil-gas type transformer bushing are simultaneously arranged in corresponding test environments, the alternating-current voltage withstand test target of the oil-gas type transformer bushing with the voltage grade of 35kV or above can be met on the transformer substation acceptance site, the electric strength is ensured, the insulation level of the oil-gas type transformer bushing is accurately evaluated, and the safe and stable operation of equipment can be ensured.
Disclosure of Invention
In order to solve the technical problem, the oil-gas type transformer bushing field test device is provided, and the technical scheme is as follows:
an oil-gas type transformer bushing field alternating-current voltage withstand test device comprises an insulating sleeve connected with an SF6 gas cylinder and a transformer oil groove connected with an oil filter, wherein the insulating sleeve is arranged above the transformer oil groove, the top of the insulating sleeve is provided with a pressurizing end, and the pressurizing end is electrically connected with the top end of a transformer side oil bushing arranged in the insulating sleeve through a conductive spring in the insulating sleeve; transformer side oil jacket bottom end is connected with the GIS side SF6 gas jacket top that sets up in the transformer oil groove, and GIS side SF6 gas jacket bottom is binding post, is by the suit in the pressure-equalizing cover, plays the voltage-sharing effect, effectively avoids point discharge.
The insulating sleeve is provided with the density relay, can accurately master the inside SF6 gas pressure size of insulating sleeve, satisfies experimental requirement, improves the measuring accuracy.
The upper end of the insulating sleeve is connected with an SF6 gas cylinder through an inflation valve, the inflation valve is a three-way valve, air in the insulating sleeve can be discharged, and SF6 gas is filled.
The lower end of the transformer oil tank is connected with the oil filter through the oil filtering valve, so that the transformer oil in the transformer oil tank can be sufficiently and circularly filtered, and the efficiency is improved.
The bottom of the transformer oil groove is of an arc-shaped structure and made of metal materials, so that the phenomena of corona, sharp angle and the like of a GIS side SF6 gas sleeve can be avoided.
The bottom of the transformer oil tank is of a flat-bottom structure and made of insulating materials, so that the phenomena of corona, sharp corner and other discharge of a GIS side SF6 gas sleeve can be avoided, and the size of the transformer oil tank can be further reduced.
The conductive spring is a compressible metal electrode, can be adjusted according to the length of the oil-gas casing pipe, and can ensure certain contact pressure with a tested object.
The top of the insulating sleeve is of a circular arc structure.
The transformer oil groove is arranged on the device bracket.
The bottom end of the transformer side oil sleeve is fixedly connected with the bottom end of the insulating sleeve through a metal flange, so that a sealed space is formed at the gap between the insulating sleeve and the transformer side oil sleeve.
And the transformer side oil sleeve is fixedly connected with the GIS side SF6 gas sleeve through a metal flange.
Compared with the prior art, the invention has the beneficial effects that: the device is completely suitable for all voltage-class oil-gas type transformer bushings, the two ends of the oil-gas type transformer bushings are simultaneously arranged in corresponding test environments, the test conditions are ensured to meet relevant standards through devices such as a transformer oil test groove, an SF6 gas insulation sleeve, a pressurizing end, a conductive spring, a metal flange, a density relay, an inflation valve, an oil filtering valve and a voltage-equalizing cover, the electric strength of the corresponding class oil-gas type bushings is ensured, the insulation level of the corresponding class oil-gas type bushings is accurately evaluated, the requirements of an alternating current withstand voltage test and a partial discharge test are met, and the aims of performing the alternating current withstand voltage test, the partial discharge test and the dielectric loss angle tangent value test on the 35kV and above oil-gas type transformer bushings in.
Description of the drawings:
FIG. 1 is a schematic view of the overall structure of the present invention;
FIG. 2 is a schematic view of the structure of the insulating sleeve of the present invention;
FIG. 3 is a schematic diagram of an oil tank structure of a transformer according to the present invention;
FIG. 4 is a flow chart of the present invention;
in the figure: 1. the transformer side oil sleeve comprises a transformer side oil sleeve, 2 and GIS side SF6 gas sleeves, 3, a metal flange, 4, a conductive spring, 5, an insulating sleeve, 6 and SF6 gases, 7, transformer oil, 8, a transformer oil groove, 9, an inflation valve, 10, a density relay, 11, a device bracket, 12, an oil filter, 13 and SF6 gas cylinders, 14, a pressurizing end, 15, an oil filter valve, 16 and a pressure equalizing cover.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
Example 1
As shown in fig. 1-4, when the electrical test is performed on the oil-gas type transformer bushing of 35kV or more, the steps are as follows:
step 1: cleaning the transformer oil groove 8 and the inner wall of the insulating sleeve 5 before testing to ensure that the inner wall is dry and clean;
step 2: qualified transformer oil is injected into the transformer oil tank 8, the bottom end of the GIS side SF6 gas sleeve 2 is placed into the transformer oil tank 8, and the top end of the GIS side SF6 gas sleeve 2 and the metal flange 3 are fixed through screws;
and step 3: sleeving an SF6 gas insulation sleeve 5 on a transformer side oil bushing 1, and fixedly connecting the SF6 gas insulation sleeve 5 with the bottom end of the transformer side oil bushing 1 through a metal flange 3 to form a sealed space at a gap between the insulation sleeve 5 and the transformer side oil bushing 1;
and 4, step 4: connecting the transformer oil tank 8 with an oil filter 12 through an oil filtering valve 15, filtering transformer oil in the transformer oil tank 8, standing for 24 hours until the oil in the transformer oil tank 8 meets the AC withstand voltage test standard, and removing the oil filtering valve 15 and the oil filter 12;
and 5: vacuumizing the interior of the insulating sleeve 5, connecting an inflation valve 9 with an SF6 gas cylinder 13 after the density relay 10 shows that the interior of the insulating sleeve 5 is completely vacuumized, inflating until the density relay 10 shows that the pressure of the gas in the insulating sleeve 5 meets the AC withstand voltage test standard, and removing the inflation valve 9 and the SF6 gas cylinder 13;
step 6: the inflation valve 9 is closed, the connection hose is disconnected, a test instrument is connected at the pressurizing end 14, and a dielectric loss tangent (tan δ) test, an alternating-current withstand voltage test and a partial discharge test are sequentially performed in this order.
Example 2
The design of the insulating sleeve 5 needs to meet the requirements of safe distance, insulating strength and vacuum degree, and partial discharge is avoided.
It will be evident to those skilled in the art that the invention is not limited to the details of the foregoing illustrative embodiments, and that the present invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein. Any reference sign in a claim should not be construed as limiting the claim concerned.
Claims (10)
1. An oil-gas type transformer bushing on-site alternating-current voltage withstand test device comprises an insulating sleeve (5) connected with an SF6 gas cylinder (13) and a transformer oil tank (8) connected with an oil filter (12), and is characterized in that the insulating sleeve (5) is arranged above the transformer oil tank (8), a pressurizing end (14) is arranged at the top of the insulating sleeve (5), and the pressurizing end (14) is electrically connected with the top end of a transformer side oil bushing (1) arranged in the insulating sleeve (5) through a conductive spring (4) in the insulating sleeve (5); the bottom end of the transformer side oil sleeve (1) is connected with the top end of a GIS side SF6 gas sleeve (2) arranged in an oil groove (8) of the transformer, the bottom end of the GIS side SF6 gas sleeve (2) is a wiring terminal, and the wiring terminal is sleeved in a voltage-sharing cover (16).
2. The oil-gas type transformer bushing field alternating current withstand voltage test device according to claim 1, characterized in that the insulation sleeve (5) is provided with a density relay (10).
3. The oil-gas type transformer bushing field alternating current voltage withstand test device according to claim 1, characterized in that the upper end of the insulating sleeve (5) is connected with an SF6 gas cylinder (13) through an inflation valve (9), and the inflation valve (9) is a three-way valve.
4. The oil-gas transformer bushing field alternating current voltage withstand test device according to claim 1, characterized in that the lower end of the transformer oil tank (8) is connected with the oil filter (12) through the filtering oil valve (15).
5. The oil-gas transformer bushing field alternating current voltage withstand test device according to claim 1 or 3, characterized in that the bottom of the transformer oil groove (8) is of an arc-shaped structure and is made of metal.
6. The oil-gas transformer bushing field alternating current voltage withstand test device according to claim 1 or 3, characterized in that the bottom of the transformer oil groove (8) is of a flat-bottom structure and is made of insulating materials.
7. The oil and gas type transformer bushing field alternating current withstand voltage test device according to claim 1, characterized in that the conductive spring (4) is a compressible metal electrode.
8. The oil-gas type transformer bushing field alternating current voltage withstand test device according to claim 1, characterized in that the top of the insulating sleeve (5) is of a circular arc structure.
9. The oil-gas transformer bushing field alternating current voltage withstand test device according to claim 1, characterized in that the bottom end of the transformer side oil bushing (1) is fixedly connected with the bottom end of the insulating sleeve (5) through a metal flange (3), so that a sealed space is formed at the gap between the insulating sleeve (5) and the transformer side oil bushing (1).
10. The oil-gas type transformer bushing field alternating current voltage withstand test device according to claim 1, characterized in that the transformer side oil bushing (1) and the GIS side SF6 gas bushing (6) are fixedly connected through a metal flange (3).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910899750.XA CN110988608A (en) | 2019-09-23 | 2019-09-23 | Oil gas formula transformer bushing on-spot ac withstand voltage test device |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910899750.XA CN110988608A (en) | 2019-09-23 | 2019-09-23 | Oil gas formula transformer bushing on-spot ac withstand voltage test device |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CN110988608A true CN110988608A (en) | 2020-04-10 |
Family
ID=70081809
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910899750.XA Pending CN110988608A (en) | 2019-09-23 | 2019-09-23 | Oil gas formula transformer bushing on-spot ac withstand voltage test device |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110988608A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111896853A (en) * | 2020-08-13 | 2020-11-06 | 搏世因(江苏)高压电气有限公司 | Oil gas casing pipe test tool |
| CN114217187A (en) * | 2021-12-14 | 2022-03-22 | 江苏核电有限公司 | Insulating tool for high-voltage end induction voltage withstand test of transformer |
| CN114675142A (en) * | 2022-03-09 | 2022-06-28 | 国网山西省电力公司电力科学研究院 | A kind of transformer bushing oil and gas discharge test device and method |
Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2365748Y (en) * | 1999-02-05 | 2000-02-23 | 武汉市江汉开关变压器厂 | Air filling light testing transformer |
| JP2001174502A (en) * | 1999-12-14 | 2001-06-29 | Toshiba Corp | High voltage test equipment |
| CN101839960A (en) * | 2010-04-09 | 2010-09-22 | 江苏雷宇高电压设备有限公司 | Complete power-frequency oil-gas partial discharge-free test transformer equipment |
| CN202119845U (en) * | 2011-05-09 | 2012-01-18 | 国网电力科学研究院 | Multifunctional extra-high voltage sleeve pipe testing fuel tank |
| CN202421414U (en) * | 2011-11-15 | 2012-09-05 | 国网电力科学研究院 | An ultra-high pressure oil-SF6 casing test device |
| CN203551694U (en) * | 2013-10-31 | 2014-04-16 | 山东泰开变压器有限公司 | Testing apparatus for transformer oil and gas sleeve outgoing line |
| CN105699813A (en) * | 2016-03-03 | 2016-06-22 | 山东电力设备有限公司 | A test device for ultra-high voltage power transformer using oil-SF6 bushing |
| CN206379244U (en) * | 2016-12-13 | 2017-08-04 | 山东鲁能泰山电力设备有限公司 | A kind of device of inspection transformer insulation structure withstanding voltage ability |
| CN207908614U (en) * | 2017-09-26 | 2018-09-25 | 西安天虹电气有限公司 | A kind of GIS cable outlets transformer high-voltage experimental rig |
| CN212180942U (en) * | 2019-09-23 | 2020-12-18 | 国网辽宁省电力有限公司丹东供电公司 | An on-site AC withstand voltage test device for oil and gas transformer bushings |
-
2019
- 2019-09-23 CN CN201910899750.XA patent/CN110988608A/en active Pending
Patent Citations (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN2365748Y (en) * | 1999-02-05 | 2000-02-23 | 武汉市江汉开关变压器厂 | Air filling light testing transformer |
| JP2001174502A (en) * | 1999-12-14 | 2001-06-29 | Toshiba Corp | High voltage test equipment |
| CN101839960A (en) * | 2010-04-09 | 2010-09-22 | 江苏雷宇高电压设备有限公司 | Complete power-frequency oil-gas partial discharge-free test transformer equipment |
| CN202119845U (en) * | 2011-05-09 | 2012-01-18 | 国网电力科学研究院 | Multifunctional extra-high voltage sleeve pipe testing fuel tank |
| CN202421414U (en) * | 2011-11-15 | 2012-09-05 | 国网电力科学研究院 | An ultra-high pressure oil-SF6 casing test device |
| CN203551694U (en) * | 2013-10-31 | 2014-04-16 | 山东泰开变压器有限公司 | Testing apparatus for transformer oil and gas sleeve outgoing line |
| CN105699813A (en) * | 2016-03-03 | 2016-06-22 | 山东电力设备有限公司 | A test device for ultra-high voltage power transformer using oil-SF6 bushing |
| CN206379244U (en) * | 2016-12-13 | 2017-08-04 | 山东鲁能泰山电力设备有限公司 | A kind of device of inspection transformer insulation structure withstanding voltage ability |
| CN207908614U (en) * | 2017-09-26 | 2018-09-25 | 西安天虹电气有限公司 | A kind of GIS cable outlets transformer high-voltage experimental rig |
| CN212180942U (en) * | 2019-09-23 | 2020-12-18 | 国网辽宁省电力有限公司丹东供电公司 | An on-site AC withstand voltage test device for oil and gas transformer bushings |
Non-Patent Citations (1)
| Title |
|---|
| 李永宁等: "智能化油气试验移动平台", 《山东电力技术》, no. 02, 15 March 2013 (2013-03-15) * |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN111896853A (en) * | 2020-08-13 | 2020-11-06 | 搏世因(江苏)高压电气有限公司 | Oil gas casing pipe test tool |
| CN114217187A (en) * | 2021-12-14 | 2022-03-22 | 江苏核电有限公司 | Insulating tool for high-voltage end induction voltage withstand test of transformer |
| CN114675142A (en) * | 2022-03-09 | 2022-06-28 | 国网山西省电力公司电力科学研究院 | A kind of transformer bushing oil and gas discharge test device and method |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN203178414U (en) | Auxiliary apparatus used for voltage withstanding test | |
| CN103809085B (en) | Termination and cable voltage method of testing for cable voltage test | |
| CN105510780B (en) | SF6 High-Voltage Electrical Appliances insulated pull rod Insulation Test system and method | |
| CN104849630B (en) | A kind of device for being used to measure gas-insulated stacked switch disc insulator defect | |
| CN102156242B (en) | Method for testing transformer insulation combination | |
| CN110988608A (en) | Oil gas formula transformer bushing on-spot ac withstand voltage test device | |
| CN101368995A (en) | Test method for GIS combined electrical appliances and plug-in transformers without removing the head | |
| CN102305903B (en) | Partial discharge detection method for pulse current of electrified operation single phase integrated gas insulated switchgear (GIS) | |
| CN202886542U (en) | Junction device for cable high-voltage resistance test | |
| CN102231309B (en) | Extra-high voltage alternating current (AC)/direct current (DC) sleeve | |
| CN212180942U (en) | An on-site AC withstand voltage test device for oil and gas transformer bushings | |
| CN201860065U (en) | Glue-impregnated capacitance type direct-current wall bushing | |
| CN211014556U (en) | GIS equipment defect simulation system and platform | |
| CN107727989A (en) | The test method of oil-gas casing structure transformer | |
| CN204758759U (en) | A device for measuring gas -insulated combination switch benzvalene form insulator defect | |
| CN110492425A (en) | A new type of indoor and outdoor terminal for high-voltage power cables | |
| CN110658434A (en) | Fault Suppression System for Co-frequency Co-phase Withstand Voltage Test of Three-phase Common Cylinder Type GIS Equipment | |
| CN210720633U (en) | GIS partial discharge detection device based on flange bolt | |
| CN207268981U (en) | A kind of new structure gas-insulated transformer casing | |
| CN209132413U (en) | A kind of auxiliary examination platform of pair of electroscope pressure test and starting test | |
| CN109613387B (en) | A winding inter-strand short circuit simulation device | |
| Lee et al. | Breakdown Voltage Characteristics on Synthetic Ester (MIDEL 7131) and Mineral Oil for Inter-turn Insulation Model of Large Power Transformer | |
| CN202678014U (en) | Overvoltage suppression resistor for detector connected with live high-voltage bus | |
| CN216718500U (en) | High tension cable outdoor termination stress cone electrical test device | |
| CN202939264U (en) | Device which carries out direct current insulation test on electrical device |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| RJ01 | Rejection of invention patent application after publication | ||
| RJ01 | Rejection of invention patent application after publication |
Application publication date: 20200410 |